What does acidic ferric chloride help recover in forensic ballistics?

Acidic ferric chloride is specifically utilized in forensic ballistics to recover serial numbers that have been obliterated or altered on firearms. When metal surfaces are engraved, the changes can lead to a stress concentration that makes the area easier to detect upon chemical treatment. Acidic ferric chloride selectively etches the surrounding metal while allowing the underlying, less affected area to remain, revealing the original serial number. This process highlights the importance of chemical restoration techniques in forensic investigations, as it can provide crucial evidence linking a firearm to criminal activity.

Understanding the role of acidic ferric chloride emphasizes its application in recovering vital identifiers that may otherwise be missed in the investigation of gun-related incidents. Other options, while relevant to the context of forensic science, involve different processes or materials not directly associated with the chemical properties of acidic ferric chloride.